1. Field of the Invention
Preferred embodiments of the present invention relate to catheters having an ultrasonic assembly. The apparatus is particularly well suited for using ultrasonic energy to enhance the therapeutic effects and/or delivery of drugs including nucleotides (DNA, RNA, and analogs thereof), medication, and other therapeutic compounds at a treatment site within the body.
2. Description of the Related Art
Several therapeutic and diagnostic applications use ultrasonic energy. For example, ultrasonic energy can be used to enhance the delivery and therapeutic effect of various therapeutic compounds. See e.g., U.S. Pat. Nos. 4,821,740, 4,953,565 and 5,007,438. In some applications, it is desirable to use an ultrasonic catheter to deliver the ultrasonic energy and/or therapeutic compound to a specific site in the body. Such an ultrasonic catheter typically includes an ultrasonic assembly for generating the ultrasonic energy. The ultrasonic catheter can also include a delivery lumen for delivering the therapeutic compound to the treatment site. In this manner, the ultrasonic energy can be used at the treatment site to enhance the desired therapeutic effects and/or delivery of the therapeutic compound.
Ultrasonic catheters have successfully been used to treat human blood vessels that have become occluded or completely blocked by plaque, thrombi, emboli or other substances that reduce the blood carrying capacity of the vessel. See e.g., U.S. Pat. No. 6,001,069. To remove the blockage, the ultrasonic catheter is used to deliver solutions containing dissolution compounds directly to the blockage site. The ultrasonic energy generated by the catheter enhances the therapeutic effects of the dissolution compounds.
Ultrasonic catheters can also be used to perform gene therapy on an isolated region of a body lumen. Gene therapy may include introduction of a gene into one or more cells to provide a gene product either not normally produced by the a cell or produced in insufficient quantities. Gene therapy also includes inhibition of the expression of an endogenous gene by antisense or co-suppression. Gene therapy may also be accomplished using molecular decoys which provide binding sites for cellular factors and thus operate as suicide molecules. As disclosed in U.S. Pat. No. 6,135,976, which is incorporated herein by reference, an ultrasonic catheter can be provided with one or more expandable sections for occluding a section of the body lumen. A gene therapy composition is delivered to the occluded section through the delivery lumen of the catheter. The ultrasonic assembly delivers ultrasonic energy to the occluded section to enhance the entry of the gene composition into the cells of the occluded section. Other uses for ultrasonic catheters include delivering and activating light activated drugs (see e.g., U.S. Pat. No. 6,176,842).
The various embodiments of the methods, devices and kits disclosed in U.S. Pat. No. 6,135,976, entitled METHOD, DEVICE AND KIT FOR PERFORMING GENE THERAPY, teach approaches to performing gene therapy at the treatment site. More specifically, U.S. Pat. No. 6,135,976 discloses approaches to performing gene therapy directly on a selected region of the body lumen. A region of the body lumen may be selected for treatment for numerous reasons, such as when the region is injured or diseased and in need of therapy. U.S. Pat. No. 6,135,976 is incorporated by reference herein and made a part of this specification.
Sometimes, however it is undesirable or impossible to perform gene therapy directly at an injured or diseased region of the body lumen. What is needed is an approach to performing gene therapy at an alternate site when it is undesirable or impossible to perform gene therapy at the injured or diseased region of the body lumen.